Re: [Dazuko-devel] dazukoFS - redirFS

[John Ogness]

Patrick Bihan-Faou wrote:
>>I have spent last few weeks trying to find the best way how to implement
>>dazukoFS (how to catch proper VFS events needed for on-access scanning).
>>One way is to use the FiST generator for transparent file systems. FiST
>>creates whole file system by duplicating VFS objects (super block, dentry,
>>inode, file) and linking them with objects in the lower layer (native file
>>system or other transparent file system). Because creating almost the
>>whole file system only to catch some VFS events is too much effort and
>>waste of time, I started to play directly with VFS object's operations.
> 
> This is interesting, but to me the greatest interest of the VFS approach
> using FiST was to benefit from the portability of FiST beyond just Linux.
> 
> How do you plan on supporting OS like Solaris or FreeBSD with this code ? It
> does sound like a duplication of effort, but I may be mistaken.
> 
> From a few of the paper that I read on the subject, I don't think that the
> processing overhead introduced by the extra work FiST does is really a
> problem.

Hi,

Aside from the fact that this is a Linux-only solution, I am concerned
that this implementation really is a deep "hack" into the Linux VFS. One
of the our goals for DazukoFS is that we gain respect from kernel
developers and perhaps be able to get into the default kernel. I think
that with this approach we will achieve neither.

I know we talked about trying to avoid VFS object duplication, but I
think that this alternative will not be acceptable.

@Patrick: My biggest concern with FiST is that it is very big and does
not give an impression of completeness. While browsing through the code,
I get the feeling that it is very much a "work in progress" and I worry
that we will need to begin doing a lot of FiST maintenance. (For
example, a FiST module won't compile on my personal workstation (FreeBSD
5.3).)

I know that Erez Zadok, the main developer of FiST, has done a lot of
good work. But I feel like the project lacks active maintenance to keep
up with modern systems and I do not know how much time Erez is able to
spend on the free version of FiST (the last release was in July 2004).

So basically I am at a loss for which direction we should take. I think
FiST is the more correct direction, but I worry that it will become a
maintenance problem for the Dazuko project (unless I or someone else got
so involved with the FiST code that we could actively maintain ourselves).

John Ogness

-- 
Dazuko Maintainer